The process of manufacturing and packaging bulk materials requires many steps. Usually, these steps include at least one step that must be continuously performed, and other steps that must be performed in batches. For example, in the manufacture of snack foods such as corn chips, other processed dry food products, and the like, the corn chips themselves are usually continuously produced in a first step to thereby send a continuous stream of corn chips down a distribution path. However, downstream of this first step, the corn chips are usually grouped into separate identifiable batches. For example, a portion of the stream of corn chips may be grouped together for the addition of seasoning or the like. Similarly, individual portions of the stream of corn chips are usually grouped together for packaging.
The distribution system for moving the bulk materials through such a process usually performs several functions. For example, the distribution system must quickly move the bulk materials along the various steps without damaging them or becoming plugged. The quickness of the distribution system is particularly important in the manufacture of bulk food items such as corn chips where there can be only a few minutes between manufacture and packaging or the quality of the shipped product is compromised.
In addition, the distribution system usually must also temporarily store materials and modulate their release downstream based on downstream capacity and demand. For example, a typical bagging process for corn chips includes a continuous stream of corn chips being delivered from the manufacturing step to a bagging area. Once in that area, a first conveyor operates on demand as needed by the bagging machinery. Should a bagging machine become full, inoperative or need maintenance, the volume of the corn chips on the conveyor can be increased without requiring the incoming continuous feed of manufactured corn chips to stop. The distribution system should operate effectively independent of the actual volume of the bulk materials within it.
It is desirable to have redundant components in manufacturing process and distribution systems. This redundancy increases production when all systems are operational and allows individual equipment within the process to be serviced or avoided as needed without outright stopping the entire production process.
The typical redundancy in a bulk material distribution system includes providing a plurality of paths after a process step in which the bulk material can travel through the system. For example, after corn chips are continuously manufactured in a first step, a plurality of redundant weighing and packaging machines are usually provided along separate individual paths downstream of the first step. One or more gates are usually provided along a path. Each gate usually includes an open and a closed position. In the open position, the flow of corn chips is deflected from the path to travel down a new path leading to a particular weighing and packaging machine. In the closed position, the flow of corn chips continues down the original path, thereby avoiding that particular weighing and packaging machine.
The gate should operate effectively and without damaging the bulk material. However, existing bulk material distribution systems and their gates tend to become less effective under certain circumstances. For example, under certain circumstances, the bulk material inadvertently joins together along the path to form a quasi-solid cohesive block.
It is difficult for this block to effectively pass through gates. For example, a common gate and path configuration in bulk material distribution systems includes the path being a vibratory conveyor, and the gate being an opening or slot in the bottom of a portion of the conveyor that has a sliding door that opens and closes on command. A trough is usually positioned below the slot such that if the door is open and the conveyor is on, the bulk material travels down the conveyor to fall through the slot. However, if the door is closed, the bulk material continues to travel down the conveyor. When the bulk material has formed into a quasi-solid cohesive block, the individual components tend to move with the block, and thereby “jump” the open slot, rather than fall down through it. Accordingly, a significant portion of the bulk material may not go to its commanded location in the distribution system. Usually, this misdirected bulk material is wasted.
Purely mechanical attempts to force the quasi-solid cohesive block of bulk material through an opened gate have several drawbacks. For example, using a mechanical arm or the like to push the bulk material into an opened gate requires the arm to touch a portion of the bulk material. In cases where the bulk material is fragile, such as corn chips, the arm tends to break the bulk material it contacts, thereby increasing the number of broken chips delivered to a consumer. Also, such mechanical structures are costly to build and install, particularly onto existing distribution systems, and they require the distribution system to be shut down for installation.